Yeah I realise that they are not the same card even after shader unlock there are some fundamental differences, that's why I had to ask. Any way I have just realised that my power supply won't cut the mustard, it's 700W. What sized power supply would I need for these two cards?

Thanks for the reply's. I'm getting pretty poor results in heaven benchmark compared to when I was running a single 6950. I have lowered my ram and cpu overclocks recently though, but I suspect it mite be something to do with how the second card is installed, it doesn't seem to fit! I have had to take out usb and front panal audio, the power and reset pins are still in the way though, the card doesn't look right. Could this be causing problems?...... Can't wait to get my RMA'd board back and loose this mATX thing.